The present disclosure relates to an image forming apparatus and a paper feed cassette.
Some image forming apparatuses, such as copiers, are provided with a paper feed cassette for storing a plurality of recording mediums (such as sheets of copy paper), detachably attached to an apparatus body of the image forming apparatus. With respect to such an image forming apparatus, a technology is suggested for automatically detecting the size of recording mediums stored in a paper feed cassette upon attachment of the paper feed cassette to the apparatus body of the image forming apparatus.
Some image forming apparatuses include a paper feed cassette that is provided with a size detection dial, and a user rotates the size detection dial to match a size mark (such as A4, A3, and B5) presented on the paper feed cassette to the size of the recording mediums stored in the paper feed cassette.
The size detection dial is provided with a plurality of notches as engaged portions on its circumference at predetermined angular intervals relative to the rotation axis. The paper feed cassette is provided with a projection as an engaging portion. Each of the engaged portions can be engaged with and disengaged from the engaging portion.
With one of the engaged portions being engaged by the engaging portion, the size detection dial is engaged with the paper feed cassette at the predetermined angular intervals. When the size detection dial in engagement with the paper feed cassette receives a rotational force equal to or greater than a predetermined value, the engaged portion comes to be disengaged from the engaging portion, which allows the size detection dial to rotate.
The size detection dial is provided with a plurality of pressure portions on its circumference at predetermined angular intervals relative to the rotation axis. When a user attaches the paper feed cassette to the image forming apparatus, at least one of a plurality of size detection switches is activated by being depressed by at least one of the pressure portions of the size detection dial, or all of the size detection switches are left unactivated by not being depressed by any pressure portion of the size detection dial. The controller of the image forming apparatus identifies the size of the recording mediums stored in the paper feed cassette based on the ON and OFF combination of the plurality of size detection switches.